Aesthetics and the ceaseless demand for miniaturization in electronics have presented great challenges for designers of electronic products. For example, due to miniaturization and aesthetics, the number of places where an antenna and its related parts can be located in a wireless communications device, such as a portable handset is becoming smaller.
In the current wireless communication environment, wireless communication devices such as cellular handsets require the ability to use multiple frequency bands, for example, to access different services. Operators of such devices, such as international travelers, may need to use the devices in regions where the local communications frequencies differ, so there is a need for a device that can accommodate different transmit and receive frequencies, which may require two antennas. In addition, recent regulations require cellular handsets to support location information for emergencies. Thus, a GPS (Global Positioning System) antenna may be required. Therefore, cellular handsets may require two or more antennas, for example, one for voice communication and one for GPS signals.
Since an additional antenna requires more space, the need for an additional antenna counters the goals of miniaturization and aesthetics. Also, metal is often used to form the housing of cellular handsets for durability and aesthetics. However, metal parts on the housing act as shields and limit the number of places where antennas can be located.
Each antenna requires a ground plane, and good antenna performance requires a large ground plane. Cellular handsets normally include a speaker or earpiece and an opening is required in the handset to permit sound to travel between the speaker and a speaker port formed in the housing. All of these factors limit the location for an antenna and requisite ground plane in typical cellular handsets.